Lovepedal Silicon Fuzzmaster  [traced]

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Lovepedal Silicon Fuzzmaster  [traced]

Postby IvIark » 03 Jun 2012, 04:32

Someone sent me a PCB layout and some pics of this through my blog and this is what I've come up with from it. Obviously open to corrections for silly mistakes because I'm not the resident tracer. Nothing much to see here I suppose, but Sean obviously has a stockpile of 2N3906's that he wants to get rid of.
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Re: Lovepedal Silicon Fuzzmaster

Postby IvIark » 03 Jun 2012, 12:36

And a vero layout to go with it.
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Re: Lovepedal Silicon Fuzzmaster

Postby Nocentelli » 03 Jun 2012, 13:02

I'm guessing you could use 2N3904 and wire as a standard negative ground circuit and it would sound similar.
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Re: Lovepedal Silicon Fuzzmaster

Postby IvIark » 03 Jun 2012, 13:03

Yes, that's why I can't understand him using the 2N3906's
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Re: Lovepedal Silicon Fuzzmaster

Postby Nocentelli » 03 Jun 2012, 13:15

IvIark wrote:Sean obviously has a stockpile of 2N3906's that he wants to get rid of.
brownwhopping wrote:How can I learn by reading threads an making circuits, when some day I can see a lawsuit or somebody beat me in the face for that?
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Re: Lovepedal Silicon Fuzzmaster

Postby mictester » 03 Jun 2012, 16:52

Minor error in the drawing. There was no DC path to the emitter of Q2 - fixed. Also, the trimmer as drawn wouldn't allow you to set the working point of the circuit. The link (in red) will correct this:

Lovepedal Silicon Fuzz Master scheme_Corrected.jpeg


Use the trimmer to set the collector of the second transistor to about 1/2 the supply voltage - experiment with setting the working point slightly either side of this point for "best" sound!

This pedal can also be radically improved by adding small value capacitors from base to collector of each transistor - start at 33p and increase until it sounds nice! This tames the excessive top fizziness and helps reduce the inherent hiss.
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Re: Lovepedal Silicon Fuzzmaster

Postby MoonWatcher » 03 Jun 2012, 17:26

IvIark wrote:Yes, that's why I can't understand him using the 2N3906's


He can probably claim that they are the secret to a better sounding silicon Fuzz Face. And people would believe him, like they usually do...
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Re: Lovepedal Silicon Fuzzmaster

Postby IvIark » 03 Jun 2012, 17:34

Chris, the link could have been tacked on the back of the board as you suggested, but the PCB layout definitely shows the 22u cap directly connected to the emitter, and that is the only connection :scratch:
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Re: Lovepedal Silicon Fuzzmaster

Postby rmroza » 03 Jun 2012, 20:54

Hey guys, sorry late to the party and appreciate all of the efforts. I started working on the PCB layout a month or so ago.
It looks like there are some err's on the PCB layout. Sorry, must have been a late night!
Let me depopulate the entire thing and ensure the PCB is 100% so we get this right and appreciate your support.
Just a couple things I note from the original PCB layout...C5 negative leg was going nowhere (should have caught that immediately), PCB layout has the trimmer TR1 middle and upper legs going to separate places, but you guys must have caught that as the stripboard was the jumper connecting the legs (this was verified and legs on VOM show continuity), further PCB layout has R2 going to R8...I think this is correct, but there is clearly a trace going up from R8 (I think to C1)!
Let me de-populate and verify a couple things!

Sorry for any inconvenience...again, must have been a late night!

p.s. - the stock settings of TR1 is: 2.73k and voltages (with 9V regulated input and all pots fully counter-clockwise):

Q1:
1 - 1.46V
2 - 6.62v
3 - 7.24V

Q2:
1 - 6.62V
2 - 7.48V
3 - 7.93V

Equinox

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Re: Lovepedal Silicon Fuzzmaster

Postby rmroza » 03 Jun 2012, 22:05

Ok, the PCB layout has been updated. There were 4 errors I found!

1. The left pin/via for R4 should go the the bottom layer (ground).
2. The top pin/via of C5 should go to the bottom layer (ground)
3. The middle pin/via of TR1 (trimmer) should also connect to the top pin/via of TR1 and top pin/via of R3 (I think you guys already caught this one)
4. The right pin/via of R8 that came from the right pin/via of R2, should connect to the negative terminal (top pin/via) of C1 and then onto the bottom pin/via of Q2.

Hopefully there is nothing else and we can finalize the schematic and stripboard!

I measured the following settings on the trimmer and transistors with 9V regulated power in and all pots turned fully counter-clockwise:

The stock setting of the 10k trimmer on the PCB layout is 2.73k

Q1:
1 - 1.46V
2 - 6.62v
3 - 7.24V

Q2:
1 - 6.62V
2 - 7.48V
3 - 7.93V

As indicated previously, yes, C1 (22uF) is connected directly to the transistor!

Equinox

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Re: Lovepedal Silicon Fuzzmaster

Postby IvIark » 04 Jun 2012, 09:49

If the right pin/via of R8 goes to C1 negative and Q2 emitter, does that mean that R2 is connected directly between Q1 base and Q2 emitter, and that R8 is now in parallel with C1 like this?

Image
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Re: Lovepedal Silicon Fuzzmaster

Postby rmroza » 04 Jun 2012, 13:27

yes. the latest PCB layout I sent you tracing should be 100% (baring no further errors)! :-)

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Re: Lovepedal Silicon Fuzzmaster

Postby IvIark » 04 Jun 2012, 14:07

OK this should be it then, this was done based on the corrected PCB:

Lovepedal Silicon Fuzzmaster Rev2.GIF
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"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP

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Re: Lovepedal Silicon Fuzzmaster

Postby IvIark » 04 Jun 2012, 14:09

And the layout. Pawel really isn't going to like this one with the extra link! Just use 2 x 50K resistors instead of the 100K and a link if you prefer mate :mrgreen:

Lovepedal Silicon Fuzzmaster Rev2.png


Updated: Shaved a column off with this one. I also don't think anyone should really bother with that unnecessary 100n filter cap at the bottom right, so you could potentially save another column there if you omit that.

Lovepedal Silicon Fuzzmaster Rev3.png
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Re: Lovepedal Silicon Fuzzmaster

Postby sinner » 04 Jun 2012, 15:40

IvIark wrote:And the layout. Pawel really isn't going to like this one with the extra link! Just use 2 x 50K resistors instead of the 100K and a link if you prefer mate :mrgreen:

Lovepedal Silicon Fuzzmaster Rev2.png


Me? I LOVE IT :mrgreen:
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Re: Lovepedal Silicon Fuzzmaster

Postby Seiche » 04 Jun 2012, 17:35

so it's basically a flipped FF (to use pnp with a regular supply) with a variable input cap and some emitter and output cap tricks.

what do the cap configurations actually achieve?
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Re: Lovepedal Silicon Fuzzmaster

Postby rmroza » 05 Jun 2012, 05:38

Hey Guys

Thanks for everyone's hard work! I think we got it right this time!!

Yes, FF with some tonal/voicing changes and good output (well above nominal) and excellent fuzz characterists and versatility to tune in what one prefers, using PNPs (that I really think I can hear and superior to NPN's I've heard, and finally negative ground, so it doesn't mess with other pedals! Great design!!

It's late, but I went over the schematic. It looks rights. Only thing I would state is if you want 100% to the original design...C4 on the schamatic and layout need to be changed to electrolytic polarized caps with negative to VR2P3.

Likewise, personally I like using the Bournes trimmers, like the 3386P-1-103LF. I will probably go 20 wide like I did on the first revision and move everything after the second link to the right to allow space for the trimmer.

I'll slam one together tomorrow to verify (if someone doesn't beat me to it).

Thanks and stay tuned!

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Re: Lovepedal Silicon Fuzzmaster

Postby Nocentelli » 05 Jun 2012, 09:21

That gain control looks odd - Surely the DC bias of Q2 will be altered from 1k-> 1k5 as the knob is twiddled with that link from junction of the 1k resistors? Doesn't that matter, or is it part of the design? I just wondered why there isn't a 2k pot with the cap wired as standard for a wider range of gain.
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Re: Lovepedal Silicon Fuzzmaster

Postby IvIark » 05 Jun 2012, 21:37

I seem to do schematics like I do layouts, and put in what I'd use rather than what was in the original. :oops: This includes that cap change:

Lovepedal Silicon Fuzzmaster Rev3.GIF
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Re: Lovepedal Silicon Fuzzmaster

Postby rmroza » 05 Jun 2012, 23:47

Thanks IvIark

I'm a stickler for detail and exact being....exact. Thanks again.

I had to order some parts. Probably be a couple days before I finalize it. Let me know if anyone else gets it completed and working. Else, I'll have it done in a couple days. Thanks.

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